Feeding mechanism for drum-type firearm



J. L. JOHNSTON EI'AL 3,101,029

Aug. 20, 1963 FEEDING MECHANISM FOR DRUM-TYPE FIREARM Filed NOV. 4, 1960 6 Sheets-Sheet 1 INVENTOR. g Anders E. HErsun JDEE MLJDMEAM 45304 an \ACZJQMM'ZL Jl L. JOHNSTON ETAL 3,101,029 FEEDING MECHANISM FOR DRUM-TYPE FIREARM,

Aug. 20, 1963 6 Sheets-Sheet 2 Filed Nov. 4, 1960 U3 INVENTOR.

Anflers E. FEH'EIEDFI BY 113521311 LJnhnsEun 1,4. Fri/7W4; Q-J. @w

J. L. JOHNSTON ETAL 3,101,029

FEEDING MECHANISM FOR DRUMTYPE FIREARM I Aug. 20, 1963 6 Sheets-Sheet 5 Filed Nov. 4, 1960 1.4. mama m4. QM

Aug. 20, 1963 J. 1.. JOHNSTON ETAL 3,101,029

FEEDING MECHANISM FOR DRUM-TYPE FIREARM INVENTOR.

BY Andrs ELFEHETSUH 6 Sheets-Sheet 4 Flled Nov 4 1960 FigA- g- 1963 J. L. JOHNSTON ETAL 3,101,029 FEEDING MECHANISM FOR DRUM-TYPE FIREARM Filed Nov. 4, 1960 6 Sheets-Sheet 5 Tier- E, INVENTOR.

Anders E. PEH'EYSDH F 3 5521311 L- Isl-1115mm Aug. 20, 1963 J. 1.} JOHNSTON ETAL 0 FEEDING MECHANISM FOR DRUM-TYPE FIREARM Filed Nov. 4, 1960 6 Sheets-Sheet 6 INVENTOR. Anders BPeHefann BY Ius E hL Iu1-m51nn United States Patent 3,101,029 FEEDING MECHANISM FOR DRUM-TYPE FIREARM Joseph L. Johnston, Hartland, Wis, and Anders G. Fetter son, Fraser, Mich assignors, by mesne assignments, to i the United States of America as represented by the Secretary of the Army Filed Nov. 4, 1960, Ser. No. 67,445 Claims. (Cl. 89-33) at the top with such opening being closed by a replaceable cover to facilitate the loading of the cartridge belt to the feeding mechanism and to make the interior readily accessible in event of any malfunction thereof.

It is a further object of this invention to provide for such guns a feeding mechanism in which the rammer is carried and guided by the replaceable cover and is symmetrically disposed therein respective to the central vertical plane of the gun and is adapted to ram the cartridges from the belt into the gun drum at the one and eleven oclock positions to provide a synnnetrical distribution of the ramming forces.

It is still another object of this invention to provide such a rammer which is connected to the operating slide of the gun for reciprocation therewith and which is stopped at the forward position thereof by contact with the rear face of the drum to prevent an overramming of the chambered cartridge which would space the cartridge primer from the firing pin and so could not be discharged.

It is another and still further object of this invention to provide for such a feeding mechanism a buffer operationally disposed so as to cushion the impact between the rammer and drum and thereby reduce counterrecoil forces produced by operating slide impact as it goes into battery position.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is a perspective, exploded view of the revolvertype gun of this invention;

FIG. 2 is a longitudinally cross-sectioned side view of the feeding mechanism and drum of the gun;

FIG. 3 is a forward extension of FIG. 2;

FIG. 4 is a view taken along line 44 of FIG. 2;

FIG. 5 is a perspective, exploded view of the feeding mechanism;

FIG. 6 is a view taken along line 6-6 of FIG. 2;

FIG. 7 is a view taken along line 7--7 of FIG. 6;

FIG. 8 is a view taken along line 8-8 of FIG. 7;

FIG. 9 is a view taken along line 9-9 of FIG. 6 showing the rammer in the battery position; and

FIG. 10 is a view similar to FIG. 9 but showing the rammer in the recoil position.

Shown in the figures is a revolver-type machine gun 12 which includes a mount 14- for attaching the rear end of the gun to a supporting structure 16. Mount 14 includes a bracket 18 for securing the mount to structure 16 so as to be immovable respective thereto. A pair of laterally spaced and longitudinally disposed rods 20 are intermediately secured by bracket 13 so as to extend both for- "ice wardly and rearwardly therefrom. A feeding mechanism 22 is mounted on the rearwardly extending sections of the rods 20 so as to be immovable respectivethereto. The remaining portion of gun 12, comprising the recoil mass thereof, is slidingly mounted on the forwardly extending sections of the rods. Whereby, feeding mechanism 22 is isolated from the recoil mass of gun 12 and is stationary relative to structure 16.

The recoil mass of gun 12 includes a drum cradle 24 which rotatingly supports a drum 26 by means of a longitudinally disposed shaft 28. A barrel 30 is replaceably mounted to the front end of a carriage 31 which is fixedly secured to cradle 24. Drum 26 is provided with five symmetrically disposed chambers 32 which respectively receive a cartridge 34 for discharge therein. Chambers 32 are disposed in drum 26 so as to be successively alignable with a bore 35 in barrel 30 when coincidental with the central vertical plane of gun 12, noted at X--X, in FIG. 4 during the bottom portion of the rotational cycle of the drum. Such position is known in the art as the six oclock position and will be referred to as such hereinafter. It is at this six oclock position that the cartridges 34 are discharged by a firing pin 37. When drum 26 is in battery, with one of the chambers 32 indexed at the six oclock position, the two chambers opposite that in the six oclock position are disposed on opposite sides of central vertical plane X-X. The one of such chambers 3-2 which is disposed on the right side of central vertical plane XX, looking forwardly from the rear end of the gun, is in a position which will be referred to as the one oclock position while the chamber on the left side is in a position which will be referred to as the eleven oclock position.

Carriage 31 is provided with an integral pair of longitndinally disposed and laterally spaced tubes 36 which slidingly receive the forwardly extending sections of the rods 20 to slidingly mount cradle 24 to mount 14. Each of the tubes '36 encases a buifer device (not shown) which is operationally interposed between the respective tubes and rods 20 for absorbing a portion of the recoil forces produced in the recoil mass of gun 12 when a cartridge 34 is discharged in drum 26. The forward end of gun 12 is supported by a sleeve 40" which is fixed to supporting structure 16 and which slidingly receives a bearing section 42 formed at the front end of a cradle extension 44 which extends forwardly from the front end of cradle 24. Whereby, the recoil mass of gun 12 is disposed for longitudinal reciprocation respective to supporting structure 16.

Drum 26 is rotated to successively index chambers 32 at the six oclock position by an operating slide 46 which is disposed in the top of cradle 24- for longitudinal reciprocation between a recoil and a battery position. Operating slide 46 is energized for movement to the recoil position by a piston 48 which is received by a cooperating cylinder So having communication with bore 35. A pair of operating springs 52 are positioned between the front end of cradle 24 and operating slide 46 so as to be energized during the recoil stroke thereof for returning the operating slide to the battery position. The translational recoil stroke of operating slide 46 is converted to a counterclockwise rotation of drum 26, for successively indexing the chambers 32 at the six oclock position, by a cam track 54 which is dispose-d in the operating slide for cooperation with five followers 56 extending radially from the outside perimeter of the drum.

Feeding mechanism 22 includes a housing 58 which has a symmetrical configuration in transversal cross-section so that a cartridge belt 60 may be fed to gun 12 from either the right or left side thereof without a change of housings. As best shown in FIG. 6, cartridge belt '60 includes a plurality of connected links 62 which are designed for gripping the cartridges 34 so as to permit longitudinal stripping therefrom.

A pair of bores 64 extend longitudinally through the base of housing 53 for receiving the rearwardly extending portions of the rods 20 and the housing is secured thereto by ball lock pins 66 so that feeding mechanism is held stationary respective to mount 14 and, therefore to supporting structure 16.

Housing 58 rotatingly supports a sprocket-wheel cluster 68 which is axially aligned to drum 26 and is coupled to shaft 28 for rotation thereby. Cluster 68 includes a cylindrical hub 69 on which there is provided a front sprocket-wheel 7t and a rear sprockehwheel '72 of similar diameter with a center sprocket-wheel 74 of smaller diameter disposed therebetween. Cluster '68 is of five-sprocket type with the sprockets forming therebetween five semicircular pockets 76 which are spaced to receive successive ones of the cartridges 34 and the associated gripping links 62 and which are each aligned with one of the chambers 32. Front sprocket-wheel 7t) is disposed for engagement with the front sections of the links 62 and rear sprocket wheel 72 With the rear sections thereof while 7 center sprocket-wheel 74 engages the central section.

Housing 58 is open at the top and such opening is closed a by a cover 7 8 which is replaceably secured to the housing by four ball-lock pins 36 so that cluster 68 is readilyaccessible in event of a malfunction of the feeding system thereat and installation of belt 60 is facilitated.

An entrance chute 82 is mounted to the right side of housing 58 for directing belt 60 thereinto over cluster 68 for engagementthereby. A track 84 is formed along the base of entrance chute so as to be slidingly engaged by tabs 85 (FIG. 7) for-med on the backs of the links 7 62 for holding the links against longitudinal displacement, respective to gun 12, when the cartridges 34 are stripped therefrom as hereinafter explained. Thebase of entrance chute 82 with track 84 extends sufficiently over cluster 68 so that the tabs 85 on the link 62 which grip the cartridge 34 disposed at the one oclock position are engagedin the track. Clearances are provided in the base of entrance chute 82 to permit theextension of cluster '68 upwardly therethrough to engage belt 60. Thereby, the base of entrance chute 82 makes contact with hub 69 so that the centerline of links '62 in entrance chute 82 is tan-gent to the pitch circles of the drum chambers. Entrance chute 82 is cut away above the base thereof at the forward end to provide a clearance 86 for the longitudinal displacement of the eleven oclock position cartridge 34 towards the aligned one of the chambers 32.

Also mounted to the right side of housing 58'is a link ejection chute -88 which maintains the engagement of links 62 with center sprocket-wheel 74, after the cartridges 34 are stripped therefrom, and directs the links out of housing 58 below entrance chute 82. A cartridge case ejection tube 92 extends longitudinally through housing 58 and is disposed therein so as to be in registry with the one of the chambers 32 which, when drum 26 is in battery, is indexed in the position which is between the one and six oclock positions and which will be referred to as the ejection position. The front end of case ejection tube 92 is enlarged to an eccentric funnel configuration so as to be in registry with the ejection position chamber 32 While the rear section of the tube is offset to pass between entrance chute 82 and link ejection chute 88 clear of cluster 68 as best shown in FIG. 6.

H Because housing 58 is symmetrical in transversal crosssection, gun 12 may be changed from one hand feed to the other, with the only changes to be made to the housing being in the interchange of entrance chute 82, link ejection chute 88 and case ejection tube 92 to the opposite sides of the housing.

7 Cartridges 34 are successively stripped from belt 60 and chambered in drum 26 by a rammer 96 which is assembled within cover 78. Rammer 96 is supported for longitudinal reciprocation in cover '78 between a pair of longitudinally disposed and laterally spaced rails 98 which are symmetrically fixed to the cover on the inside thereof for sliding engagement by mating grooves 100 in the rammer. Thus, rammer 96 is carried by feeding mechanism 22 and is removed therefrom along with cover 78 after release from slide 46. I

Rammer 96 is connected to operating slide 46 for re ciprocation therewith by a shaft 102 which extends longitudinally forward from the rammer and is joined'to the operating slide by a transversely disposed pin 164. Shaft 192 extends slidingly through a bore 1136 in a boss 108 centrally disposed on the top of rammer 26. Bore 106 is counterbored from the front end to form an annular shoulder 110 which is contactableby an annular flange 112 on shaft M2 for transferring the recoil movement of operating slide 46 to rammer 96; Shaft 102 extends rearwardly beyond boss 1% and is provided with a threaded section at the rear end for threadingly mounting a nut 114 which is backed by a washer 116. A coil spring 118 is mounted on the rearwardly extending section of shaft 102 between washer 116 and boss 108 and is preloaded to resiliently hold flange 112 in contact with shoulder M0 and so interpose a buffer between rammer 96 and operating slide 46.

Rammer 96 includes a first ram 12! which depends therefrom for contact with the base of cartridge 34 indexed at the one oclock position so as to strip such car:

tridge from the associated link- 62 and position it partially within the aligned one of the chambers 32 during forward displacement of the rammer. In order to prevent eccentric ramming forces which would tend to force the rammed cartridges downward, resulting in a misalignment with the receiving chamber 32, first ram 120 includes an arm; 121 which extends diametrically across the base of the cartridge. Rammer 96 also includes a second ram 122 which depends therefrom forwardly of first ram 120 and imposition to engage at the eleven oclock position the base of cartridge 34 which during the preceding operating cycle had been partially chambered by the first ram, thereby completing the chambering of such cartridge during the forward displacement of the rammer. The forward movements of rammer 96 and operating slide 46 are stopped by the contact of the rammer with the rear face of drum 26 with spring 118 cushioning the impact therebetween. With the forward position of rammer 96 being determined by the rear face of drum 26, the cartridges 34 are not overrammed into drum 26 which would prevent primers of the cartridges being contacted by firing pin 37.

In operation, when cartridge 34 is discharged at the six oclock position, the discharge gases cause a rearward displacement of operating slide 46 and rammer 96. Through the, engagement of cam track 54 in operating slide 46 with the engaged one of the followers 56, drum 26 is rotated one pitch, during the final travel of the operating 7 slide to the recoil position and the initial displacement therefrom, to align succeeding chamber 32 with'bore 35 of the barrel 30 at the sixoclock position and move the expended case into registry, with case ejection chute 92 recoil stroke of operating slide 46 energize the operating slide for the return stroke. During such return stroke, first ram 120'pushes cartridge 34 in the one oclock position from the associated link 62 and part way into the aligned chamber 32'. Simultaneously, second ram 122 contacts the base of cartridge 34 which was partially chambered during the previous cycle and completely chambers it in the aligned chamber as rammer 96 contacts drum 26 to stop forward movement of such rammer. When rammer 96 contacts drum 26, operating slide 46 is resiliently stopped in battery position for discharge of the cartridge chambered at the six oclock position.

From the foregoing it is clearly apparent that there is provided herein a revolver type machine gun which has many advantages over others provided in the art. These advantages include the symmetrical configuration of housing 58, whereby feed may be changed from one hand to the other without change of housings; the replaceable cover 7 8, whereby the loading of belt 60 to feeding mechanism 22 is greatly facilitated and the interior thereof is easily accessible in event of any malfunction thereat; the installation of rammer 96 to the cover so as to be removable therewith and so as to be symmetrically disposed relative to the central plane of the feeding mechanism for an even distribution of ramming forces; the disposition of the rammer for contact with the rear face of the drum when in the forward position to prevent an overramming of the chambered cartridge; and the disposition of spring 118 between the rammer and operating slide 46 to cushion the impact thereof when going into battery position and thereby reduce counterrecoil forces in such operating slide.

Although a particular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

We claim:

' '1. In a machine gun including a rotatable drum provided with a plurality of chambers successively indexable at positions relative to the central vertical plane of the gun, the positions including a six :oclock position which coincides with the central vertical plane of the gun at the lower inner section therewith and a one oclock and an eleven oclock position disposed above the six oclock position equidistantly from and on opposite sides of such plane, a feeding mechanism including a housing which is symmetrical in transversal cross-section with an opening in the top to provide easy access to the interior thereof, a cover removably mounted to said housing for covering the opening, sprocket means rotatingly disposed in said housing and coupled to said drum for rotation therewith, said sprocket means being adapted to draw a cartridge belt into said housing and to index the cartridges in the belt in alignment with thechambers indexed at the one oclock and eleven oclock positions, and a rammer slidingly disposed in said cover for contact with the bases of a the cartridges indexed by said means at the one oclock and eleven oclock positions for a stepped transfer from the cartridge belt into said chambers in such positions.

2. The machine gun as defined in claim 1 wherein said rammer is connected in longitudinal relationship to a reciprocable operating slide for reciprocation therewith and is disposed for contact when in a forward position with the upper segment of the rear face of said drum to prevent an overramming of the cartridges into said chambers and stop said operating slide in a battery position.

3. A machine gun including a recoil mass slidingly mounted on the front sections of a pair of rods secured by bracket means to a supporting structure, said recoil mass including a cradle, a drum rotatiugly supported by said cradle, a plurality of cartridge chambers disposed in said drum so as to be successively indexable at positions relative to the central vertical plane of the gun, said positions including a six oclock position which coincides with such plane at the lower intersection therewith and a one oclock and an eleven oclock position disposed above the six oclock position equidistantly from such plane and on opposite sides thereof, an operating slide disposed on said cradle above said drum for reciprocation to and from a battery position responsive to discharge forces, cam means operationally interposed between said operating slide and said drum for converting reciprocation of said operating slide to rotation of said drum, a feeding mechanism mounted :on the rear sections of said pair of rods so as to be stationary respective to the supporting structure, said feeding mechanism including a housing which is symmetrical in transversal cross-section for receiving a linked belt with cartridges from either side, an opening in the top of said housing to provide easy access to the interior thereof, a cover removably mounted on said housing for covering said opening, a rammer mounted by rail means to said cover symmetrical to the central vertical plane for longitudinal reciprocation, means for connecting said rammer to said operating slide for reciprocation therewith, and means cooperating with said rammer for transferring the cartridges in a two-step operation from said belt into the chambers indexed at the one and eleven oclock positions.

4. The machine gun as defined in Cliillll'l 3 wherein said rammer is disposed for contact with the rear face of said drum when said rammer is in the forward position and said operating slide is in battery position and :Wherein said means for connecting said rammer to said operating slide includes a longitudinally disposed shaft which is connected by pin means to said operating slide, a boss on said ramrner provided with a bore to slidingly receive said shaft for moveable extension therethrough, a shoulder formed in said bore by a counterbore introduced from the front thereof, an annular flange disposed on said shaft for contact with said shoulder for transferring recoil movement of said operating slide to rearward movement of said rammer, a nut-backed washer mounted on the rear end of said shaft, a spring disposed on said shaft between said boss and said nut-backed washer and preloaded to form a buffer for cushioning the contact between said rammer and drum and reducing the impact forces in said operating slide when going into battery position.

5. The machine gun as defined in claim 3 wherein said feeding mechanism includes sprocket means rotatable with said drum for drawing said belt into said housing and for indexing the cartridges in said belt successively at the one and eleven oclock positions, and wherein said rammer includes a first ram contactable with the base of the cartridge in the one oclock position for partial transferral thereof from said belt into the aligned one of said chambers during forward movement of said rammer, and a second ram disposed for contact with the base of the partially transferred cartridge at the eleven oclock position to complete the charrrhering thereof simultaneously with the partial transferral of the cartridge at the one oclock position by said first ram.

References Qited in the file of this patent UNITED STATES PATENTS 1,377,236 Watson May 10, 1921 2,365,459 Dobremysl Dec. 19, 1944 2,454,251 Hamilton Nov. 16, 1948 2,504,994 Lochhead Apr. 25, 1950 2,619,875 Ashworth et al Dec. 2, 1952 2,803,169 Linke Aug. 20, 1957 2,820,400 OBrien Jan. 21, 1958 2,845,006 OBrien July 29, 1958 2,950,652 O Brien Aug. 30, 1960 2,979,992 Colby Apr. 18, 1961 

1. IN A MACHINE GUN INCLUDING A ROTATABLE DRUM PROVIDED WITH A PLURALITY OF CHAMBERS SUCCESSIVELY INDEXABLE AT POSITIONS RELATIVE TO THE CENTRAL VERTICAL PLANE OF THE GUN, THE POSITIONS INCLUDING A SIX O''CLOCK POSITION WHICH COINCIDES WITH THE CENTRAL VERTICAL PLANE OF THE GUN AT THE LOWER INNER SECTION THEREWITH AND A ONE O''CLOCK AND AN ELEVEN O''CLOCK POSITION DISPOSED ABOVE THE SIX O''CLOCK POSITION EQUIDISTANTLY FROM AND ON OPPOSITE SIDES OF SUCH PLANE, A FEEDING MECHANISM INCLUDING A HOUSING WHICH IS SYMMETRICAL IN TRANSVERSAL CROSS-SECTION WITH AN OPENING IN THE TOP TO PROVIDE EASY ACCESS TO THE INTERIOR THEREOF, A COVER REMOVABLY MOUNTED TO SAID HOUSING FOR COVERING THE OPENING, SPROCKET MEANS ROTATINGLY DISPOSED IN SAID HOUSING AND COUPLED TO SAID DRUM FOR ROTATION THEREWITH, SAID SPROCKET MEANS BEING ADAPTED TO DRAW A CARTRIDGE BELT INTO SAID HOUSING AND TO INDEX THE CARTRIDGES IN THE BELT IN ALIGNMENT WITH THE CHAMBERS INDEXED AT THE ONE O''CLOCK AND ELEVEN O''CLOCK POSITIONS, AND A RAMMER SLIDINGLY DISPOSED IN SAID COVER FOR CONTACT WITH THE BASES OF THE CARTRIDGES INDEXED BY SAID MEANS AT THE ONE O''CLOCK AND ELEVEN O''CLOCK POSITIONS FOR A STEPPED TRANSFER FROM THE CARTRIDGE BELT INTO SAID CHAMBERS IN SUCH POSITIONS. 